Biomedical subjects

Rogério de Oliveira

Publications and source records attributed to Rogério de Oliveira.

4 recordsLinked to original sources

PubMed2005

Effect of a carbamide peroxide bleaching gel containing calcium or fluoride on human enamel surface microhardness.

This in vitro study evaluated the surface microhardness of human enamel submitted to bleaching with 10% carbamide peroxide (CP) containing calcium or fluoride. Ninety-eight dental blocks (5 x 5 mm2) with polished enamel surfaces were randomly assigned to 7 treatment groups (n=14), as follows: without bleaching and storage in artificial saliva (control); 10% CP; 10% CP + 0.05% calcium; 10% CP + 0.1% calcium; 10% CP + 0.2% calcium; 10% CP + 0.2% fluoride; and 10% CP + 0.5% fluoride. During 14 days, enamel surfaces were daily exposed to a 6-h bleaching regimen followed by storage in artificial saliva. Surface microhardness was measured before (baseline), during (7th day), immediately after bleaching (14th day) and 1 week post bleaching. Data were analyzed by two-way ANOVA and Tukey's test (p<0.05). All treatments reduced SM significantly during the bleaching cycle (7th day), immediately after bleaching (14th day) and 1 week post bleaching, compared to baseline and to the unbleached control group. In conclusion, in spite of the addition of calcium and fluoride, all bleaching treatments affected the enamel surface microhardness.

Calcium↗

PubMed2003

Effects of a carbamide peroxide agent and desensitizing dentifrices on enamel microhardness.

PURPOSE: To evaluate the in vitro microhardness of enamel treated with a 10% carbamide peroxide agent and two desensitizing dentifrices at different bleaching times. MATERIALS AND METHODS: A 10% carbamide peroxide bleaching agent was evaluated (Rembrandt 10%) (REM). A placebo agent was used as a control group (PLA). The bleaching and the placebo agents were applied to human enamel dental fragments for 8 hours per day, followed by immersion for 5 minutes in a slurry solution of desensitizing dentifrices: Sensodyne (S) or Sensodyne Fluor (SF). During the remaining time, the enamel fragments were individually stored in 13.5 ml of artificial saliva. Knoop microhardness measurements were performed at baseline, 8 hours, 7, 14, 21, 28, 35 and 42 days of treatment and at 7 and 14 days of a post-treatment period. RESULTS: Analysis of variance and Tukey's test showed no differences in enamel microhardness for REM + SF (P=0.069) and PLA + SF (P=0.93) within each time interval. The dental fragments treated with REM + S and PLA + S showed an increase in microhardness values within each time interval (P<0.0001). There were significant differences among the treatment agents from the 28th to the 56th day. The use of 10% carbamide peroxide bleaching and a desensitizing dentifrice significantly increased the enamel microhardness values during the bleaching treatment and after 14 days after the completion of the treatment. After the post-treatment period, the enamel fragments treated with a placebo agent and with a 10% carbamide peroxide agent and with a desensitizing fluoride dentifrice maintained the baseline values.

Carbamide Peroxide↗

PubMedDate not supplied

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology.

The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect--10% carbamide peroxide (10% CP), Colgate Platinum--10% CP, Day White 2Z--7.5% hydrogen peroxide (7.5% HP), Whiteness Super--3% CP, Opalescence Quick--35% CP and Whiteness HP--35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM). Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%), and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.

Carbamide Peroxide↗

PubMedDate not supplied

Effect of peroxide-based bleaching agents on enamel ultimate tensile strength.

This study evaluated the effects of peroxide bleaching regimens on the ultimate tensile strength (UTS) of human enamel. A resin composite block was built-up on the bonded occlusal surface of 14 extracted, sound, erupted third molars to enable posterior preparation for the microtensile test. The bonded teeth were serially sectioned in a buccal-lingual direction into approximately 0.7-mm thick slices. Each slice was trimmed with a fine diamond bur to reduce the area of the buccal, internal slope of the cusps to a dumb-bell shape with a cross-sectional area of less than 1 mm2. The samples were randomly divided into seven groups (n = 10): unbleached control group and bleached groups treated with six bleaching regimens. The specimens were tested in tension at 0.5 mm/minute and the data were analyzed by ANOVA and Tukey test. Specimens from the control group presented 51.3 +/- 8.6 MPa, while the UTS of bleached enamel ranged from 22.0 +/- 5.6 to 36.3 +/- 9.1 MPa. All bleaching procedures significantly reduced enamel UTS (p < 0.05). Differences were also observed among treatments. The results suggested that bleaching regimens can significantly reduce enamel UTS.

Analysis of Variance↗